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United States Patent |
6,103,007
|
Wu
,   et al.
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August 15, 2000
|
Inorganic resin compositions, their preparation and use thereof
Abstract
Inorganic resin compositions comprising, in combination, an aqueous
solution of metal phosphate, an oxy-boron compound, a wollastonite
compound and other optional additives, inorganic composite articles and
products reinforced by fillers and fibers including glass fibers obtained
from these compositions and processes for preparing said products.
Inventors:
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Wu; Xiao (Brussels, BE);
Gu; Jun (Brussels, BE)
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Assignee:
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Vrije Universiteit Brussel (Bussels, BE)
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Appl. No.:
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077005 |
Filed:
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July 10, 1998 |
PCT Filed:
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November 17, 1995
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PCT NO:
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PCT/BE95/00106
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371 Date:
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July 10, 1998
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102(e) Date:
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July 10, 1998
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PCT PUB.NO.:
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WO97/19033 |
PCT PUB. Date:
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May 29, 1997 |
Current U.S. Class: |
106/690; 106/18.12; 106/18.14; 106/286.1; 106/286.2; 106/286.3; 106/286.4; 106/286.5; 106/286.8; 106/287.1; 106/287.29; 106/287.3; 106/691; 427/397.7 |
Intern'l Class: |
C04B 028/34; 287.3 |
Field of Search: |
106/18.12,18.14,690,691,286.1,286.2,286.3,286.4,286.5,286.6,286.8,287.1,287.29
427/397.7
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References Cited
U.S. Patent Documents
3804651 | Apr., 1974 | Semler | 106/690.
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4792359 | Dec., 1988 | Barrall et al. | 106/691.
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Foreign Patent Documents |
2 291 951 | Jun., 1976 | FR.
| |
23 56 524 | May., 1975 | DE.
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30 43 856 | Jun., 1982 | DE.
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2 100 246 | Dec., 1982 | GB.
| |
Other References
Hitachi Chemical Co., "Inorganic Binder For Mica Plate Manufacture," Dec.
26, 1983, Chemical Abstracts, vol. 99, No. 26.
Zhou Wenbin, "Inorganic Binder For Manufacturing Mica Sheets," Nov. 26,
1990, Chemical Abstracts, vol. 113, No. 22.
|
Primary Examiner: Green; Anthony
Attorney, Agent or Firm: Jacobson, Price, Holman & Stern, PLLC
Claims
What is claimed is:
1. An inorganic resin composition which comprises, in combination, as
component A an acidic aqueous solution of metal phosphate containing
phosphoric acid, as component B an oxy-boron compound, and as component C
a wollastonite compound.
2. The composition according to claim 1, wherein the metal phosphate is
selected from the group consisting of an aluminum phosphate, zirconium
phosphate, magnesium phosphate, zinc phosphate, calcium phosphate, iron
phosphate, and mixtures thereof.
3. The composition according to claim 1, wherein said oxy-boron compound is
selected from the group consisting of boric acid and hydrates thereof, an
alkali metal and alkaline-earth metal salt of boric acid and hydrates
thereof, an amine and ammonium salt of boric acid and hydrates thereof,
and mixtures thereof.
4. The composition according to claim 3, wherein said oxy-boron compound is
selected from the group consisting of boric acid and hydrates thereof,
sodium borate and hydrates thereof, ammonium borate and hydrates thereof,
calcium borate and hydrates thereof, and mixtures thereof.
5. The composition according to claim 3, wherein said oxy-boron compound is
present in a powder or liquid form.
6. The composition according to claim 1, wherein said wollastonite compound
is a natural or synthetic wollastonite, in calcined or non-calcined state,
or a combination thereof.
7. The composition according to claim 1, wherein said component A
comprises, per 100 parts by weight of said wollastonite compound
calculated on a basis of pure calcium silicate in said wollastonite
compound:
said metal phosphate in an amount that contains 14 to 135 parts by weight
of phosphorous pentoxide and
2 to 65 parts by weight of metal oxide.
8. The composition according to claim 7, wherein said component A
comprises:
said metal phosphate in an amount that contains 24 to 86 parts by weight of
phosphorous pentoxide and
5 to 47 parts by weight of metal oxide.
9. The composition according to claim 1, wherein a water content of the
composition is from 8 to 150 parts by weight per 100 parts by weight of
said wollastonite compound calculated on a basis of pure calcium silicate
in said wollastonite compound.
10. The composition according to claim 9, wherein the water content is from
11 to 95 parts by weight.
11. The composition according to claim 1, wherein said oxy-boron compound
is present, calculated on an anhydrous basis, in an amount of 0.2 to 50
parts by weight per 100 parts by weight of said wollastonite compound
calculated on a basis of pure calcium silicate in said wollastonite
compound.
12. The composition according to claim 11, wherein said oxy-boron compound,
calculated on an anhydrous basis, is present in an amount of 2 to 20 parts
by weight.
13. The composition according to claim 6, wherein a particle size and an
aspect ratio of the wollastonite are not larger than 150 .mu.m and 10
respectively.
14. The composition according to claim 1, which further comprises an
additive selected from the group consisting of fibres, a filler, a foaming
agent, a surfactant, a pigment, and a combination thereof.
15. The composition according to claim 14, wherein said surfactant is zinc
stearate.
16. The composition according to claim 14, wherein said foaming agent is a
carbonate, in a powder form or in an aqueous solution, selected from the
group consisting of calcium carbonate, magnesium carbonate, sodium
carbonate, potassium carbonate, and a combination thereof.
17. The composition according to claim 14, wherein said filler is silica or
a derivative thereof.
18. The composition according to claim 14, wherein said additive is a fibre
selected from the group consisting of metal fibre, organic fibre, and
non-metal inorganic fibre.
19. The composition according to claim 1, in the form of a cured shape.
20. The composition of claim 18 in the form of a cured, prepreg shape.
21. The composition of claim 18, wherein the fibre is glass fibre.
22. The composition of claim 20, wherein the fibre is glass fibre.
23. A process for preparing an inorganic resin composition in the form of a
cured shape, said composition comprising, in combination, as component A
an acidic aqueous solution of metal phosphate containing phosphoric acid,
as component B an oxy-boron compound, and as component C a wollastonite
compound, which process comprises:
mixing said acidic aqueous solution of metal phosphate with said oxy-boron
compound at a temperature and for a time sufficient to form a further
aqueous solution,
contacting said wollastonite compound with the further aqueous solution to
form a slurry, and
applying said slurry on a surface, wherein said slurry sets to the form of
the cured shape of the inorganic resin composition.
24. The process according to claim 23, which further comprises maintaining
said slurry at a temperature sufficiently low to retard a setting reaction
before being brought on said surface.
25. The process according to claim 23, wherein said surface comprises a
fibre mat made of fibres selected from the group consisting of inorganic,
organic and/or metallic fibres.
26. The process according to claim 25, whereby applying the slurry on said
fibre mat effects impregnating said fibre mat with said slurry, whereby
said slurry sets to the form of a cured, fibre reinforced shape.
27. The process according to claim 23, wherein said surface is comprised of
metal, organic, or inorganic material.
28. A process for preparing an inorganic resin composition in the form of a
cured, prepreg shape, which composition comprises, in combination, as
component A an acidic aqueous solution of metal phosphate containing
phosphoric acid, as component B an oxy-boron compound, and as component C
a wollastonite compound, and which composition further comprises a fibre
selected from the group consisting of metal fibre, organic fibre, and
non-metal inorganic fibre, which process comprises:
mixing said component A, said component B, said component C to form a
slurry,
impregnating fibres with said slurry to form a prepreg,
maintaining said prepreg at a temperature sufficiently low to prevent
curing thereof, and
applying said prepreg on a surface that supports said prepreg, wherein the
slurry in said fibres sets to the form of the cured, prepreg shape.
29. A method of using an inorganic resin composition comprising
incorporating said composition as a binder into a coating or surfacing
agent, said composition comprising in combination, as component A an
acidic aqueous solution of metal phosphate containing phosphoric acid, as
component B an oxy-boron compound, and as component C a wollastonite
compound.
30. A method of using an inorganic resin composition, which composition
comprises, in combination, as component A an acidic aqueous solution of
metal phosphate containing phosphoric acid, as component B an oxy-boron
compound, and as component C a wollastonite compound, and which
composition further comprises a fibre selected from the group consisting
of metal fibre, organic fibre, and non-metal inorganic fibre, said method
comprising incorporating said cured prepreg shape into a coating or
surfacing agent.
31. The method of claim 30, wherein the shaped form has a foamed structure.
Description
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to inorganic resins in composition of aqueous
solution of inorganic metal phosphate, oxy-boron compound and wollastonite
compound; to various additives for said composition; to processes for
forming said resin and the resin product; to products manufactured by said
resin composition and said process. The unique feather of this invention
is that pot life of the fresh resin and temperature increase of the resin
during setting reaction can be controlled so that its pot life can be
between few minutes to an order of magnitude of several hours or longer;
whereas hardened resin and resin product have good material properties and
wide range of use. Both cellular and non cellular structures can be
obtained.
The resin of the present invention can be used as adhesives and binders. In
terms or properties, inorganic resin of the present invention and its
products lies between those such as e.g. Portland cement and those such as
e.g. technical ceramics. Fresh mixture or the resin has low viscosity, is
storable at low temperatures and easy to use; while the hardened resin is
strong, durable, resistant against mild acid attack, fire-proof, and
stable at high temperatures. It is suitable to make, such as but not
limited, adhesives, binders, coatings and inorganic composites reinforced
by fillers and fibres including all glass fibres, used both at low and
high temperatures.
2. Description of the Related Art
Wollastonite has been employed not long time ago as primary material in
phosphate cement compositions. Only few formulations are known in that
field so far, they all have quick setting characteristics. Hardening of
these compositions usually occurs at ambient condition in a range from
several minutes to ca 10-20 minutes after forming of the cement, which is
practically-impossible to be used in applications such as that of
composite materials. Large amount of heat production is another typical
phenomenon of the traditional phosphate cements which may produce defects
inside of the material and affects negatively on material properties. When
wollastonite is employed as primary material in the composition, the quick
setting may result in extra voids and cracks in structure of the material
due to formation of CO.sub.2 during the setting process produced by
decomposition of calcite (CaCO.sub.3) contained in the wollastonite, which
further undermines strength and durability of the material. U.S. Pat. No.
3,804,651 dated Apr. 16, 1974 to C. E. Semler discloses a quick setting
gel binder of phosphate solutions and wollastonite. The cured binder shows
a good mechanical strength and durability, but its fresh mixture gels
quickly and is claimed as a quick setting composition. U.S. Pat. No.
4,375,516 dated Mar. 1, 1983 to Jeffery L., Barrall et.al discloses a
material in composition of aluminium phosphate solution and solid
component containing wollastonite. This composition usually sets in
several minutes in the temperature range of 4-25.degree. C. U.S. Pat. No.
4,792,359 dated Dec. 20, 1988 to Jeffery L., Barrall et.al discloses a
method to prepare composite materials by hot pressing the mixture of
phosphate cement and varies fibres at about 85.degree. C. under pressures,
which takes advantage of the quick setting.
As a summary, these inorganic phosphate compositions are found not related
to this invention. In terms of composition, no oxy-boron compound is used
to extend pot life of these phosphate cement compositions; in terms of
setting time, all available compositions has a quick setting; in terms of
pot life during which period the mixture keeps flowable, no information is
available probably due to the quick setting; in terms of application, all
available compositions is used for purposes which needs quick setting.
The inorganic resins of the present invention have a controllable pot life
and temperature increase in its fresh state; and have good material
properties for the hardened resin, such as, e.g., good mechanical
strength, durability, resistance against mild acid attack, high scratch
hardness, non flammability, high temperature resistance, and good adhesion
with other materials such as fibres including glass fibres,
SUMMARY OF THE INVENTION
The inorganic resins of the present invention are formed basically by
reactions between three components, either physically separated or mixed
or in combination thereof. The component A is an aqueous solution of metal
phosphate preferably selected from the group consisting of aluminium
phosphates, zirconium phosphates, magnesium phosphates, zinc phosphates,
calcium phosphates, iron phosphates, including derivatives and mixtures
thereof. It should be understood that the term solution of the component A
is used broadly herein to include aqueous reaction mixtures, and the term
derivative of metal phosphates herein includes all types of phosphate such
as polyphosphate and dihydrogen phosphate. The component B comprises
oxy-boron compound including its hydrates. The component C comprises
wollastonite compound. Fillers and fibres including glass fibres can be
introduced to the inorganic resin of this invention to improve material
properties. Cellular structures of the inorganic resin can be produced by
employing foaming agents and surfactants.
Being formed by contacting all ingredients together by way of such as
intermixing, fresh resin of this invention has an adjustable pot life in
the range from several minutes to an order of magnitude of several hours
or longer, and correspondingly a setting time from few minutes to several
hours or longer at ambient temperatures; has a controlled temperature
increase during setting reaction; while the hardened resin has very good
material properties. The composition of the present invention interacts
and is able to set without the use of externally applied heat. These
compositions and their unique characteristics such as the extended pot
life distinguish themselves from the other traditional phosphate cements
in the related field. Hardened resin of this invention has a three
dimensional network structures. Due to this nature, inorganic resins of
the present invention are formulated to be essentially strong, durable,
resistant against environmental attack such as acid rain, non flammable,
and stable at high temperatures.
Inorganic resin of this invention has good adhesion with fibres, meanwhile
it shows no attack against fibres including glass fibres. Accordingly
qualified inorganic composites can be produced by this invention. Products
made by inorganic resin of this invention can replace at least a portion
of presently known products based on organic resins, traditional cements
and ceramics in a wide range of applications, such as, fibre reinforced
composite products; moulded configurations in cellular and non-cellular
structures; thermal, electrical and/or acoustical insulations; binders and
adhesives; coatings and or surfacing agents; patching compositions and the
like. Further, the use of inexpensive materials and easy processing
compared to that of typical organic resins or ceramics offers a number of
advantages over many of the organic resins and ceramics destined for
similar applications.
It is therefore one objective of the present invention to provide a range
of inorganic resin compositions with the above mentioned feathers and
advantages.
Another objective of the present invention is to provide processes to
prepare these resin compositions and resin products, as well as the use
thereof.
These and other objectives and advantages of the present invention will
become apparent from, the detailed description given hereafter by way of
non limiting examples.
DETAILED DESCRIPTION OF THE INVENTION
The inorganic resins of the present invention are formed basically by
reactions between three components, either physically separated or mixed
or in combination thereof. The component A is an aqueous solution of metal
phosphate preferably selected from the group consisting of aluminium
phosphates, zirconium phosphates, magnesium phosphates, zinc phosphates,
calcium phosphates, iron phosphates, including derivatives and mixtures
thereof. It should be understood that the term solution of the component A
is used broadly herein to include aqueous reaction mixtures, and the term
derivative of metal phosphates herein includes all types of phosphate such
as polyphosphate and dihydrogen phosphate. The component B comprises
oxy-boron compound including its hydrates. The component C comprises
wollastonite compound including natural and synthetic wollastonite, in
calcined or non-calcined state. Fillers and fibres including glass fibres
can be introduced to the inorganic resin of this invention to improve
material properties. Cellular structures of the inorganic resin can be
produced by employing foaming agents and surfactants. Having homogeneously
mixed, the said components interact in a controlled way so that designed
pot life and setting time can be obtained. Setting process of said
inorganic resin is in general exothermic, but the temperature increase of
the resin during the reaction can be controlled. Inorganic resin of this
invention may set at ambient temperatures to form a strong, durable
monolithic mass without applying external heat.
In accordance with this invention, the most important ingredient to prepare
the component A is phosphoric acid aqueous solution including but not
limited, e.g., ortho-phosphoric acid, pyro-phosphoric acid and
polyphosphoric acid, used either alone or in combination thereof.
Phosphoric acid is commercially available, with the 85 percent by weight
being the most common concentration for the ortho-phosphoric acid. Other
phosphorous based acids may also be satisfactory to practice the present
invention, providing that the overall water content of the reaction system
is not too high. As a general rule, the phosphoric acid will be suitable
if it contains the phosphorous, expressed as P.sub.2 O.sub.5, in range of
14 to 135 parts by weight with respect to 100 parts by weight of
wollastonite in the component C, with 24 to 86 parts by weight being
preferred.
To practice the present invention, metal phosphate which is relatively
insoluble in water is preferred to be used in the component A. It is found
that metal phosphate selected from the group consisting of aluminium
phosphates, zirconium phosphates, magnesium phosphates, zinc phosphates,
calcium phosphates, iron phosphates, including derivatives and mixtures
thereof, is preferred. With respect to 100 parts by weight of wollastonite
in the component C, suitable amount of equivalent metal oxide contained in
the metal phosphate, i.e., aluminium oxide, zirconium oxide, magnesium
oxide, zinc oxide, calcium oxide and iron oxide, is in the range of 2 to
65 parts by weight, with 5 to 47 parts by weight being preferred.
In accordance with this invention, the amount of water employed in the
component A should be carefully controlled. Excessive water can convert
the resin into a thin mixture that will cause sedimentation of solid
particles such as the wollastonite, which leads to an inferior product.
Insufficient water will not wet the dry particles adequately to allow the
necessary chemical reaction. The amount of water influences on
concentration of the reactive components and consequently affects on the
pot life and setting process of the resin. The optimal amount of water
will depend upon the very metal used in component A and the particular
physical characteristics of the constituents of dry particles of this
invention, e.g., absorbency, surface area, etc. However, it must be
sufficient to adequately wet the dry particles, such as the wollastonite
and fillers and/or fibres, to form desirable mixture. This optimal amount
of water can be determined on a blend by blend basis. With respect to 100
parts by weight of wollastonite in the component C, the amount of water
used can range from about 8 to 150 parts by-weight, with from 11 to 95
parts by weight being preferred. The water content in the component A
should include, for purposes of calculation, any water of hydration from
the compounds in the component A, B and C.
In accordance with this invention, the component A can be basically
prepared by mixing metal and/or metal oxide and/or metal phosphate
including hydrates and derivatives thereof in phosphoric acid aqueous
solution at a temperature and for a time sufficient to form at least a
semi-transparent solution. Sometimes only a particle-liquid suspension is
obtained after long time mixing due to such as impurities contained in the
raw materials. A filtration process is then required to remove the
undesolved portion of particles larger than 1 .mu.m from the solution. The
filtered solution can be employed to practise this invention if it
contains desired amount of said ingredients. A clear solution homogeneous
in molecular level without discrete particle distribution is preferred. It
may be with or without color depends on the very metal employed.
In general, the component A of this invention is a mixture composed of
various types of phosphate, including but not limited, i.e.
orthophosphate, pyrophosphate, and polyphosphate, appeared either alone or
in combination thereof. Exact distribution of the different phosphate
structures depends on the method and raw materials employed to make the
solution, and on the age of the solution. However, a transparent solution
with an age of 3 months at 20.degree. C. is found generally sufficient to
practice this invention by any person skilled in the art. The component A
can be prepared all together as one liquid, or prepared separately and
then mixed together as one liquid, or prepared separately and kept
separately prior to use.
In accordance with this invention, the component B of this invention is
composed of oxy-boron compound including its hydrates. The oxy-boron
compound actively participates into the setting reaction, results in the
very structure of the fresh resin of this invention with which the pot
life can be controlled.
The oxy-boron compound used in this invention generally comprises these
boron compounds containing at least one boron-oxygen linkage, hereafter
termed the oxy-boron compound. The oxy-boron compound is found specially
effective in this invention in terms of producing a extended pot life,
avoiding setting expansion and resin over-heating during the setting,
i.e., temperature increases to more than 100.degree. C. when free water in
the composition boils. These compounds include, e.g., oxy acids of boron
which contain one or more boron atoms such as, e.g., boric acid; salts of
such acids, such as the alkali metal and alkali earth metal salts thereof,
such as sodium borate, calcium borate and amine or ammonium salts thereof
such as ammonium borate; and ester of such acids, such a; trialkoxy borate
and triaryloxy borate, e.g., trimetal borate. Boron-containing starting
materials which yield oxy-boron additives upon contact with phosphate
solutions of the component A can be used to generate the oxy-boron
compounds in situ. The preferred oxy-boron compound include boric acid,
the alkali metal and alkali earth salts of the boric acid such as the
sodium borate, calcium borate including their hydrates. The oxy-boron
compound can be used as a dry powder or as a solution by dissolving them
in water or phosphoric acids. The amount of the component B used in the
composition of this invention can vary according to the degree of
retardation and the temperature increase desired. Generally, with respect
to 100 parts by weight of wollastonite in the component C, the amount of
the oxy-boron compound in the mixture, calculated on an anhydrous basis,
ranging from about 0.2 to 50 parts by weight, preferably from about 2 to
20 parts by weight being suitable.
In accordance with this invention, the component C is the wollastonite
compound including natural and synthetic wollastonite, in calcined or
non-calcined state. Usually the commercially available wollastonite is a
mineral of natural calcium silicate (CaSiO.sub.3) of acicular structure,
with a theoretical composition of 48.3% CaO and 51.7% SiO.sub.2 by weight.
This wollastonite can be classified into two categories of low aspect
ratio and high aspect ratio. The low aspect ratio wollastonite, commonly
with aspect ratio of not higher than 10, including that of about 1, is
mainly used as flux and fillers in ceramic, metallurgical, construction
and coating application. The high aspect ratio wollastonite commonly with
aspect ratio of 10-20 is used as fibres to produce effect of
reinforcement. The most important properties of the wollastonite that
affect behavior of the inorganic resin of the present invention are their
loss on ignition (LOI), aspect ratio, granulometry, and wollastonite
content. Those characteristics can change from one wollastonite to
another, depends on its mineral origin, geological history and processing
technique to obtain the wollastonite. Setting process of the inorganic
resin of the present invention is in one way or another influenced by
origin of the wollastonite, which broadly includes factors such as e.g.
geological history, way of fabrication and impurities of the wollastonite.
Loss on ignition of the wollastonite is due to release of CO.sub.2 when the
calcite (CaCO.sub.3), which is intimately associated with the
wollastonite, is decomposed into CO.sub.2 and CaO at high temperatures. To
practise this invention, the less amount of associated calcite that can be
achieved, the better the wollastonite will be. However, for a practical
reason, certain amount of CaCO.sub.3 content up to about 5 percent by
weight is present in the commercially available wollastonite. High amount
of the calcite contained in the wollastonite is not desired, because it
will produce excessive CO.sub.2 during mixing and reaction stage, which
results in internal defects and undermines mechanical strength. High
calcite content of the wollastonite will also lead to a long mixing time
in order to achieve a homogeneous mixture thus increase difficult for
material processing. High amount of the calcite present in the composition
may disturb the three component reaction of this invention due to high
reactivity between the calcite and the phosphate solution of the component
A, which may lead to undesirable reactions and weak structures. One way to
completely eliminate the calcite is to heat the commercial available
wollastonite in a range of 550-1000.degree. C. until the calcite
decomposes to CaO and CO.sub.2. The calcination process seems to produce
no harmful effect on using the calcined wollastonite in this invention. To
practice this invention, the range of the LOI value between
20-1000.degree. C. should not be more than 3 percent by weight. Using a
mixture of calcined and non-calcined wollastonite is preferred with which
the LOI value can be completely controlled.
Granulometry of the wollastonite plays an important role in controlling pot
life and setting time of the inorganic resins of the present invention.
When the grain size is too small, the resin will be too reactive and lead
to a short pot life. However, when the grain size is too large, only part
of wollastonite is able to participate into the reaction so that the
necessary constituent to form backbone of the structure is insufficient.
Coarse wollastonite will also cause the particle sedimentation from the
resin mixture due to its larger specific gravity (about 2.9). However,
compared to traditional phosphate cement, this invention permits to use
the wollastonite with relatively larger grain size due to the extended pot
life, during which period the wollastonite will be decomposed to a
satisfactory degree. To practice this invention, the wollastonite used as
primary reactant is preferred not larger than 150 .mu.m. The range of the
particle size distribution is given in terms of having a product with
preferred properties. Wollastonite with particle size larger than 150
.mu.m may also be used in the composition as reactive fillers and/or
fibres to improve properties of the resin product.
According to the present invention, aspect ratio of the wollastonite used
as primary reactant should not be too high to avoid wollastonite fibre
from entanglement during mixing which makes the mixing difficult. A
preferable aspect ratio is not larger than about 10 which can produce
desirable rheology and the wollastonite solubility in the solution of
metal phosphate. Wollastonite content of the commercial wollastonite
product is preferred to be more than 90 percent by weight. Wollastonite
with aspect ratio of larger than about 10, and/or purity less than about
90 percent by weight may be included in general as reactive fillers and/or
fibres to reinforce the inorganic resin of the present invention.
In accordance with this invention, inorganic resins of the present
invention can be packed and kept separately until prior the use in a three
package system. However, a two package system is preferred which comprises
a liquid phase and a solid phase. In accordance with this invention, the
liquid phase may be composed of the component A and the component B, the
solid phase may be composed of the component C. The wollastonite compound
may also be partially mixed with the component A, or with the mixture of
the component A and component B. The remaining portion of the wollastonite
compound is kept separately until prior the use. To practise this two
package system, mixing of the component A and the component B can be
performed at a temperature and for a time sufficient to form an aqueous
solution wherein the oxy-boron compounds are dissolved and incorporated in
said metal phosphate. Sometimes a solution with large particle suspension
is obtained, then a filtration process is required to remove particles
larger than 1 .mu.m from the solution-provide that all necessary said
components is present.
In accordance with this invention, setting process of the inorganic resin
or present invention can be controlled by adjusting, such as, liquid/solid
weight ratio, water content or the component A, granulometry of the
wollastonite. The manner of changing these parameters, whether alone or in
combination may depend on various factors such as type of product desired
and/or the type of equipment utilised. In accordance with this invention,
the setting process can also be adjusted by curing temperatures. High
temperatures will increase reactivity of the resin, shorten setting
process and produce more exothermic heat; on the other hand; low
temperatures will reduce reactivity of the resin and prolong the setting
process. This provides a large room for engineers to design and
manufacture the composites based on inorganic resin of this invention,
which is not possible for the traditional phosphate cements. It can be
noted that the true scope and spirit of this invention is to provide a
unique composition with controllable pot life for the fresh mixture and
good material properties for the hardened resin. This includes both quick
setting and extended setting. The few minutes setting time allows for
quick repairing work, while the extended pot life permits to make
composite materials using various available processing techniques.
In accordance with this invention, inorganic resin composition may be fully
cured at ambient temperatures within a limited duration. For example, at
20.degree. C., the resin of this invention may be fully cured within 3
days in terms of developed strength and structural stability. Demoulding
may however take place earlier, such as when the resin finally sets. The
resin can be cured in an open condition or closed condition, or in
combination thereof. Usually the resin shows nearly no setting shrinkage
when cured at ambient conditions, profile of any complicated configuration
can be copied, and the resin products have a good surface finish. The
cured resin has a good resistance against water in terms of the dimension
stability and chemical leaching, for instance, being immersed into water,
pH value of the water keeps neutral, both the resin and the water is
tasteless. Those properties are much similar to that of organic polymer
based resin, so that existing processing technique for organic and/or
cement composite materials can be employed to make inorganic composite
products based on this invention.
In principle, the resin products which are obtained do not require heat
curing and may be placed in boiling water without adverse effect. The
inorganic resin of the present invention can be placed in a desired
configuration, the components interact and harden into a monolithic body
with a desired shape. However, curing and/or post curing at high
temperatures and high pressures might be recommended to convert the resin
into the final structures, when the resin products are destined for use at
high temperature and/or in high pressure conditions. In general, the post
curing process can further improve material properties of the inorganic
resin.
It is found that setting time of the fresh mixture of the present invention
can be significantly prolonged at a temperature sufficiently low to retard
any setting reactions, so that the mixture remains viscous and/or gel like
or as a slurry without setting. Being gradually heated up, such as to
ambient temperatures, the resin of this invention will resume its
reactivity and set without negative effects on its material properties. A
preferred method to practise this nature is to mix the resin composition
and then keep the fresh mixture or slurry at the low temperatures. This
nature provides a way to store the fresh resin for later use, it reduces
waste and makes the resin easy to handle. By contacting the wollastonite
compound in the solution of phosphates with the oxy-boron compound for a
sufficiently long time, large solid particles of the wollastonite may be
decomposed, resulting in a slurry containing much smaller solid particles
or even no discrete solid particles. The inorganic resin as a slurry
treated at a temperature sufficient low to prevent any setting reaction
may be used as a matrix material to make a fibre reinforced composite or
prepreg in which the fibres may be well impregnated. In practice, said
slurry or said prepreg is then brought on a surface capable of supporting
said slurry or said prepreg respectively, the slurry reacting to set as a
shaped product of the inorganic resin or said prepreg.
It is observed that the inorganic resin of the present invention has a very
good adhesion to other materials such as e.g., metals, organic and
inorganic material such as the concrete based on the Portland cement. It
has also good adhesion with fibres, such as, e.g., carbon fibres, organic
fibres, such as e.g., polyester fibres, mineral fibres, such as, e.g.,
rockwool, metallic fibres and glass fibres, such as, e.g., E-glass fibres.
The good adhesion between fibre and matrix is essential for composite
materials to impasse the load from matrix to the fibre, thus increase
strength and stability of the composites. With these advantages, inorganic
resins of this invention can be used to prepare composite materials
reinforced by fibres, such as, i.e., glass fibres.
Aggregate and refractory as long as they do not produce negative effect on
material properties, preferably graded sand of mullite, silica, mica,
cordierite, silicon carbide, can be included in the dry blend in a
controlled amount as filler to make the resin concrete of this invention,
for improving performance and reducing cost of the resin product. Fillers
can generally enhance the strength of the hardened resin product. Filler
usage may range up to about 90 percent by weight of the total composition.
Other materials which can be used include particles of competent rocks or
rock-forming minerals such as granite, basalt, dolomite, ansesite,
feldspar, amphibole, pyroxene, olivine, gabbro, rhyolite, syenite,
diorite, dolerite, peridotite, trachyte, obsidian, etc., as well as
materials such as slag, fly ash of pulverised coal and that from corundum
production, glass cullet, wood whips, and fibrous materials such as metal
fibres, glass fibres, organic fibres and natural fibres. When intended to
be used at high temperatures, refractory fillers may employed, for
instance, the refractory oxides, carbides, nitride, and silicides, such as
aluminium oxide, lead oxide, chromic oxide, zirconium oxide or silicate,
silica, silicon carbide, titanium nitride, molybdenum disilicide and
carnonaceous material such as graphite. In general, these fillers can be
with different particle size, and can be both with cellular and
non-cellular structures. Mixtures of the fillers can be used, when
desired, including mixtures of metals and the ceramics.
Characteristically, hardened resin concrete of this invention is strong and
durable. Toughness of the resin product can be achieved by adding fibres.
The resin product of present invention has a good resistance against
environmental attack, such as freezing (-20.degree. C.)/thawing
(20.degree. C.) cycles in terms of mechanical strength and dimension
stability of the resin product. The resin product of present invention has
also a good resistance against acid attack, such as H.sub.2 SO.sub.4
solution of pH=1.5. Softening point of the inorganic resin itself is above
1100.degree. C.
It is discovered that, surprisingly, articles based on the inorganic resin
of the present invention has a very high surface scratch hardness when
abrasion resistant fillers, such as, silicon carbide, boron carbide,
corundum, garnet, emery, silica and mixtures thereof, are used. The
surface scratch hardness for the resin itself is about 6 Moh in wet and
dry condition, but it can be significantly increased to 8.5 Moh or higher
in dry condition, and 8 Moh or higher in wet condition when the abrasive
grains are included in the inorganic resin composition.
In accordance with this invention, additives such as foaming agents and
surfactants can be added to the freshly mixed inorganic resin so that
shaped articles with cellular structures with different bulk densities can
be produced. In general, carbonates are the suitable species to produce
uniform foaming of inorganic resin of this invention, although other
foaming agents may also provide satisfactory results. Foaming is caused by
CO.sub.2 decomposed from carbonates when contacting with acidic phosphate
solutions. Carbonates such as MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3, Li.sub.2
CO.sub.3 and the like, or mixture thereof, which produce relatively
insoluble phosphate can be used, with CaCO.sub.3 and MgCO.sub.3 being
preferred. Other carbonates such as Na.sub.2 CO.sub.3 and K.sub.2 CO.sub.3
which produce relatively soluble phosphate salts may also be employed
where leaching of the phosphate from the product in wet condition is not
considered as a problem. The foaming agents can be added to the fresh
resin of this invention at any moment before setting, however, they can
also be premixed with the component C of this invention. Because the
foaming is produced gradually, it is undesirable to have the setting prior
to complete foaming. For that reason, this invention is very advantages
over traditional phosphate cements to produce cellular structures because
of the extended setting. Furthermore, because of the extended pot life,
this invention leaves sufficient time to place the fresh mixture of the
inorganic resin into any complex mould configuration, so that a foamed
resin product with good surface finish can be obtained.
In accordance with this invention, surfactant which is not affected by
phosphoric acids may be added into the resin to promote cell stability
when making cellular structures. The surfactant may be premixed with the
component C of this invention, or added to the freshly formed resin
mixture before adding the foaming agent, so that the surfactant can be
distributed homogeneously over whole volume of the composition. The
surfactant might be, such as, e.g., zinc stereate.
Various pigments, both organic and inorganic as far as their coloring
effect is not influenced by phosphoric acids and they have no negative
effect on the inorganic resin of this invention, can be added to the resin
to have colored resin products. The pigments can be used either as powder
or liquid or in combination thereof.
Generally, the inorganic resin of the present invention can be used as a
binder both at low and high temperatures. In the field of composite
materials, due to the controlled pot life and setting process, fibre
reinforced composite can be produced using available material processing,
such as, e.g., the hand lay-ups, the spray technique, the extrusion, the
pultrusion and the hot pressing, wherein the resin impregnates the fibres
and/or fibre mats to form a fibre reinforced product. The product based on
inorganic resin of this invention can be strong and tough due both to the
resin and function of fibres. The invention is generally applicable as
inorganic binder to prepare, like but not limited, as coatings and/or
surfacing agents such as e.g. fire resistance and corrosion resistance
coatings; adhesives such as to bind metals and/or woods; special cements
and concretes, such as dental material, with various characteristics,
e.g., high strength and low leachate.
The inorganic resin of present invention can be applied indoors or outdoors
to concrete drives, storage yards, warehouse and factory floors to repair
and restore damaged surfaces. The resin can be used in the field of
roadway construction, roadway patches and building reparation or other
load bearing purposes. The characteristics of any particular concrete
structures formed can depend on weight ratio of the various compounds, the
nature of the aggregate employed, the curing conditions as well as other
factors. Due to good adhesion between the inorganic resin of this
invention and other cement products, such as that based on the Portland
cement, the inorganic resin can be used to fill structure cracks in slabs,
and repair highway median barrier walls. This resin can also be used in
situation requiring in general a quick, permanent repair of concrete. The
resin can be used to make pipes, ducts, moulded configurations in cellular
and non-cellular structures; thermal, electrical and/or acoustical
insulations; light weight products and the like because of its moisture
resistance, high dielectric properties and cellular structures.
The following experiments illustrate various embodiments of the invention.
The amounts of the various constituents are given in parts by weight.
Other embodiments will be apparent to one of ordinary skill in the art
from a consideration of this specification or practice of the invention
described therein. It is intended that the specification and experiments
are considered as exemplary only, with the true scope and spirit of the
invention being indicated by the claims which follow the examples.
As an examplary, a basic resin composition without additives in accordance
with this invention is shown in Tab.1.
TABLE 1
______________________________________
Component A*
Component B Component C
______________________________________
Fe.sub.2 O.sub.3
0.7 Na.sub.2 B.sub.4 O.sub.7.10H.sub.2 O
6.0 Wollasto-
70.0
nite
Al.sub.2 O.sub.3
4.3 Calcined
30.0
wollasto-
nite
ZrO.sub.2
6.3
ZnO 13.1
P.sub.2 O.sub.5
55.3
H.sub.2 O
57.3
______________________________________
*analytical result.
The component A, expressed by oxide according to oxide analysis, is
prepared by dissolving Fe.sub.2 O.sub.3, Zr(OH).sub.4, granular reagent
grade zinc metal, and aluminium pellets in extra pure quality, together
with balanced amount of water, in 85% orthophosphoric acid solution by
mixing at about 90.degree. C. until a clear solution is obtained. This
solution is kept at an ambient temperature of about 20.degree. C. for 6
months before use. The component B is Na.sub.2 B.sub.4 O.sub.7.10H.sub.2
O, commonly known as borax. It is a dry powder with grain size less than
70 .mu.m and in extra pure quality. The wollastonite of the component C
has an aspect ratio of about 5, and 99.5 percent by weight of the
wollastonite is not more than about 70 .mu.m. Part of the wollastonite is
calcined at 800.degree. C. and kept at 800.degree. C. for a duration
sufficient to get all CaCO.sub.3 decomposed to CaO and CO.sub.2.
In practice of this invention, the component A and component B are firstly
pre-mixed together by a mechanical mixer at about 90.degree. C. for about
24 hours to form an aqueous solution. The wollastonite and calcined
wollastonite in the component C are also pre-mixed, then added to above
mentioned solution and mixed by a planetary mixer at about 20.degree. C.
to form a fresh resin of this invention. The composition and procedure to
prepare the resin of this invention will be referred as basic resin
composition and basic preparation procedure hereafter.
EXAMPLE 1
Examples of controlled pot life and initial setting time are shown in
Tab.2.
TABLE 2
______________________________________
Component
Component B Initial
A Na.sub.2 B.sub.4 O.sub.7.10H.sub.2 O
Component C
Pot life*
set time
______________________________________
see Tab.1
0 see Tab.1 10 min.
20 min.
see Tab.1
2 see Tab.1 20 min.
1 hour
see Tab.1
4 see Tab.1 30 min.
10 hours
see Tab.1
6 see Tab.1 2.5 hours
17 hours
see Tab.1
10 see Tab.1 7 hours
24 hours
______________________________________
*the duration in which the resin keeps flowable
The fresh resin is formed by said basic resin composition and basic
preparation procedure. Curing of said resin is at an ambient temperature
of about 20.degree. C. in a covered condition. The results shown in the
Tab.2 illustrate that pot life of the resin can be controlled so that both
quick setting and extended setting of the resin can be obtained by
addition of the component B. The pot life herein means the duration in
which the fresh resin keeps flowable. The composition without the borax
has a pot life of only 10 minutes which is too short to further add
fillers or fibres, meanwhile the temperature of the mixture increases to
more than 100.degree. C. during the reaction and it sets almost instantly.
On the other hand, the resins of this invention induce less temperature
increase and they are able to harden gradually. In general, more component
B is used, less temperature increase, more extended pot life and longer
initial setting will be. Further more, inorganic resins of this invention
have good surface finish.
EXAMPLE 2
The inorganic resin has said basic inorganic resin composition and is made
by said basic preparation procedure. This resin has a pot life of about
2.5 hours and initial setting of about 17 hours at 20.degree. C. in
covered condition. The resin gets slightly warm during setting process
with free water liberation but no noticeable setting shrinkage or
expansion. Being cured at 20.degree. C. for 3 days in a covered condition,
the specimen is demoulded and subjected to further drying or wetting
before mechanical test. 3-points bending test shows that said resin has an
average bending strength of 18.4 MPa, flexural modulus of 13.8 GPa when
dried at 20.degree. C. for 3 days; bending strength 12.3 MPa and flexural
modulus 12.0 GPa when immersed into water at 20.degree. C. for 3 days.
EXAMPLE 3
Two laminates are prepared by hand lay-ups. The matrix of the first
laminate is the resin made from said basic resin composition and said
basic preparation procedure, that of the second laminate is the polyester.
Each of the laminates is made with 4 layers of the same unidirectional
E-glass fibre mat. The laminates are cured at an ambient temperature of ca
20.degree. C. for 24 hrs in covered condition and then post cured at
60.degree. C. for another 24 hours in uncovered condition.
TABLE 3
______________________________________
Max Max Modulus E.sub.f V.sub.f
V.sub.f strain load GPa GPa
Matrix vol % % N measured
calculated
______________________________________
Inorganic
14.0 1.90 7388.9 10.2 10.6
resin*
Polyester
22.6 1.91 8659.4 17.8 17.2
______________________________________
*Inorganic resin of this invention
Results of tensile test are shown in the Tab.3, where the strain is a mean
value of the strain measured by strain gauge on both sides of the samples;
the V.sub.f is the fibre volume fraction, E.sub.f is the modulus of the
glass fibre, The E.sub.f V.sub.f is calculated assuming E.sub.f =76 GPa.
It is observed that, for both laminates, their cracks are spreaded
uniformly transversal to the fibre direction after the matrix break, and
there is no delamination occurred before final rupture of the fibres.
EXAMPLE 4
The resin has said basic composition and made by said basic preparation
procedure. The hardened resin is subjected to the freezing (-20.degree.
C.)/thawing (20.degree. C.) cycles for 30 times, the sample shows no
noticeable dimension change and cracks.
EXAMPLE 5
The resin has said basic composition and is made by said basic preparation
procedure. Additional 200 parts by weight of mullite of 0-0.5 mm is added
as filler. Curing is performed in a covered mould at an ambient
temperature of 20.degree. C. for 7 days, then demoulded and left uncovered
in the ambient condition for 3 days. Scratch hardness on cut surface of
the hardened resin is about 8.5, and there is no noticeable crack or
dimension change when immersed in H.sub.2 SO.sub.4 solution of pH=1.5
during 14 days.
EXAMPLE 6
The resin has said basic composition and is made by said basic preparation
procedure. The fresh resin is made at an ambient temperature of ca
20.degree. C. and then left at -20.degree. C. immediately. It remains
flowable for several days and then gradually evolves to a gel without
setting at -20.degree. C.
EXAMPLE 7
Composition of a foamed resin of this invention is shown in Tab.4, it is
made by said basic preparation procedure. The surfactant is zinc stereate,
the fibre is E-glass fibre. The MgCO.sub.3 is added to the resin after
other ingredients being mixed. Mixture of this composition foams gradually
and sets at 20.degree. C. without applying external heat. The foamed resin
is strong and it has a bulk density of about 350 kg/m.sup.3 and has
uniform cell structures.
TABLE 4
______________________________________
Component A*
Component B Component C Additives
______________________________________
Fe.sub.2 O.sub.3
0.7 Na.sub.2 B.sub.4 O.sub.7
2.0 Wollasto-
100.0
MgCO.sub.3
5.0
.10H.sub.2 O nite
Al.sub.2 O.sub.3
4.3 Surfac-
1.0
tant
ZrO.sub.2
6.3 Talc 10.0
ZnO 13.1 Fibre 0.5
P.sub.2 O.sub.5
55.3
H.sub.2 O
57.3
______________________________________
*analytical result.
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